It only makes money for them if the individuals sitting there all day actually makes purchases. Fortunately, most people understand that there is an unspoken agreement that the "free" wifi comes with the caveat that a purchase will be made and use it appropriately. There are always those few people that can make a coffee last for 3 hours while they use the system but thankfully these are the minority. I completely and strongly disagree with your premise that it is harmless to share wifi passwords as it encourages some people to "leech" off the system without making a purchase. And some of your justification, not wanting to bother the employees by asking for the password, is ludicrous. If this was a problem for businesses they would put up a sign with the password rather than a sign that the business offers wifi (I think it's understood by most people that this is for patronizing the business).